In the past, blade producers often had problems with their mould shells suffering small deformations that increased with the number of blades produced, gradually becoming major errors in the blade shape. These deformations are caused by cycles of heating and cooling while the mould is under some pressure or load. Essentially the mould shell slowly becomes stretched out of shape as many blades are produced. This deformation overwhelmingly occurs in the cross section shape of the blade mould, as the two spanwise edges are normally supported by the sturdy steel backing frame.
It has earlier been proposed by the present Applicant to provide a mould with center shape adjustment devices, which are provided at the shell surface and provide adjustments only perpendicular to the shell surface, and flange shape adjustment devices, which are provided at the spanwise flanges of the mould and provide adjustments both perpendicular to and parallel with the shell surface. Particularly, the center shape adjustment devices and the flange shape adjustment devices comprise threaded adjustment devices. While the proposed adjustment devices did achieve the goal of making shape adjustment fast and easy, they suffered from some unexpected disadvantages:    1. When turning over the upper mould, the shell tended to move somewhat freely in the widthwise direction. This can cause unwanted shape change of the shell.    2. There is some slack in the threaded adjustment devices such as turnbuckle devices between the mould frame and the mould shell. This causes the gap at the joint between the two moulds to be difficult to regulate.
Further, it was found by experiment that:    1. Adjustment of the mould shape in the direction normal to the mould surface is quite Necessary in the middle area of the mould.    2. Adjustment of the mould shape in the direction normal to the mould surface is not normally required at the edges of the mould. However adjustment in the direction parallel to the mould surface (e.g. horizontally) is still important to regulate the width of the mould.